This program, which is now in 35th year under this grant, seeks basic information concerning relations between glucose metabolism and the functional properties of neurons by studying the relatively simple sympathetic and dorsal root ganglia of vertebrates. These ganglia are readily accessible because they lie outside the central nervous system. The initial approach was to determine the effects of neuronal activity on metabolism of glucose and lipids in adult mammalian sympathetic ganglia. More recently the approach has turned to the metabolism during embryonic development that builds the structures needed for synaptic transmission and impulse conduction. The proposed investigations, to be conducted on sympathetic ganglia from chicken embryos, include (a) continuation of studies on the effects of changes in the volume and composition of the incubation medium on glucose metabolism, (b) the uptake and oxidation of other possible energy-yielding substrates in the presence of glucose, (c) measurement of the metabolic rate through the pentose cycle in chemically activated sympathetic ganglia, for comparison with the rate in resting ganglia, and (d) a search for a sympathetic ganglion preparation from chicken embryos that would be suitable for studying the metabolic effects of naturally conducted impulses as functions of the age of embryonic development. Excised ganglia will be incubated in bicarbonate-buffered media containing labeled glucose or other substances labeled with 14C while continuously recording labeled CO2 output. At the end of incubation constituents of the tissue and products in the bathing medium will be resolved chromatographically and their contents of labeled carbon will be measured. These studies in the discipline of neurochemistry will contribute to basic knowledge about glucose and lipid metabolism and about embryological development in vertebrate neural tissues, especially the sympathetic nervous system, which is important in cardiovascular control. They thus may be relevant to understanding these processes in various disease states, such abnormal development, neurological disorders caused by metabolic disturbances, and circulatory deficiencies related to malfunction of the sympathetic nervous system.